1. Field of the Invention
The present invention relates to a sheet storing apparatus which stores image-formed sheets on a stack tray after performing a post-processing such as a binding process while stacking the sheets temporarily on a processing tray and a sheet aligning mechanism which stacks sheets on the stack tray in an orderly manner.
2. Description of Related Arts
In general, there has been widely known a sheet storing apparatus which stacks and stores sheets with images formed thereon by an image forming apparatus on a stack tray. Among such storing apparatuses, there has been also known a sheet storing apparatus which has a function of performing a post-processing such as a binding process while temporarily stacking sheets conveyed to a sheet discharging port on a processing tray which is arranged between a sheet discharging path and a sheet placement face of a stack tray and subsequently storing the sheets on the stack tray.
For example, Japanese Patent Application Laid-Open No. 2009-35371 (Patent Document 1) discloses an apparatus in which a sheet conveyed from an image forming apparatus is introduced to a sheet discharging path, a processing tray is arranged at the downstream side of a path sheet discharging port with a step therefrom, and a stack tray is arranged at the lower side thereof with a step further therefrom. Patent Document 1 also discloses a conveyance switching mechanism in which a reversing roller capable of being rotated forwardly and reversely is arranged at a position distanced from the sheet discharging port of the sheet discharging path, a leading end of a sheet conveyed from the sheet discharging port is received by a reversing roller, and reverse rotation of the roller conveys the sheet to the processing tray and forward rotation of the roller conveys the sheet to the stack tray.
Thus, the sheet conveyed from the sheet discharging path is stored at the stack tray as being conveyed in the sheet discharging direction and is stored at the processing tray as being conveyed in the direction opposite to the sheet discharging direction. With such a path configuration, a predetermined distance is formed between the sheet discharging port of the sheet discharging path and an introducing port of the stack tray. In the apparatus of Patent Document 1, a space is formed between the sheet discharging port of the sheet discharging path and the reversing roller and the processing tray is arranged therebelow. This is to arrange a large distance (space) between the sheet discharging port and the reversing roller and to arrange the processing tray therebelow for miniaturization and compactification of the apparatus.
Here, in order to reliably convey a sheet to a reversing roller which is distanced from a sheet discharging port of a sheet discharging path, there has been known to form a plurality of corrugated-plate-shaped corrugations in the sheet width direction on a sheet conveyed by a sheet discharging roller, traditionally.
Japanese Patent No. 4591579 (Patent Document 2) discloses a sheet discharging mechanism in which a guide rib protruded between roller nipping points is arranged between sheet discharging roller pairs which are arranged at a predetermined interval to form concavo-convex corrugations on a sheet conveyed from a sheet discharging roller. Such a sheet discharging mechanism reinforces a sheet which is difficult to be conveyed in a linear direction such as a soft thin sheet and a curled sheet by forming corrugations in a direction perpendicular to the sheet conveying direction thereon. According to the above, the sheet conveyed by the sheet discharging roller is conveyed farther to the downstream side on a linear trajectory.
Similarly, in Japanese Patent No. 3604262 (Patent Document 3), a guide rib protruded between rollers is arranged at the upstream side of the sheet discharging roller pairs which is arranged in plural lines as being mutually distanced to form a plurality of corrugations on a sheet and a guide plate arranged at the roller downstream side presses the sheet to correct curls thereof. According to the above, a conveyance force is reliably provided to a sheet nipped by the roller pair and the sheet is corrected thereafter.